package medium;

import java.util.HashMap;
import java.util.Map;

/**
 * Created by daodao on 2017/12/1.
 * Problem 3
 * Description: Given a string, find the length of the longest substring without repeating characters.
 *
 * Examples: Given "abcabcbb", the answer is "abc", which the length is 3.
 * Given "bbbbb", the answer is "b", with the length of 1.
 * Given "pwwkew", the answer is "wke", with the length of 3.
 * Note that the answer must be a substring, "pwke" is a subsequence and not a substring.
 */
public class LongestSubstringWithoutRepeatingCharacters {
    public static int lengthOfLongestSubstring(String s) {
        if ("".equals(s)) {
            return 0;
        }
        int longestSubLen = 0;
        Map<Character, Integer> map = new HashMap<Character, Integer>();
        for (int i = 0, j = 0; i < s.length(); i++) {
            if (map.containsKey(s.charAt(i))) {
                j = Math.max(j, map.get(s.charAt(i)) + 1);
            }
            map.put(s.charAt(i), i);
            longestSubLen = Math.max(longestSubLen, i - j + 1);
        }
        return longestSubLen;
    }
}
